The first city walls of Dubrovnik were probably built in the 7th century, but the walls that can be seen today were built only from the 14th/15th century, with extensions until the 17th century. They vary in thickness from 4.9 to 16.4 ft (1.5 to 5 meters), depending on their location. They are considered one of the most impressive examples of medieval fortifications and have never been breached since their construction - not by the Venetians, not by Napoleon's army, and not by the Yugoslav People's Army with its modern weapons in the 1990s. Not only does the complex make a difference in terms of military history, it is also simply beautiful to look at and offers a fantastic view over the old town and the Mediterranean Sea.